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Moore GG, Mack BM, Wendt KL, Castano-Duque L, Anderson VM, Cichewicz RH. Genomic and metabolomic diversity within a familial population of Aspergillus flavus. Mol Microbiol 2024; 121:927-939. [PMID: 38396382 DOI: 10.1111/mmi.15244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 01/12/2024] [Accepted: 02/11/2024] [Indexed: 02/25/2024]
Abstract
Aspergillus flavus is an agriculturally significant micro-fungus having potential to contaminate food and feed crops with toxic secondary metabolites such as aflatoxin (AF) and cyclopiazonic acid (CPA). Research has shown A. flavus strains can overcome heterokaryon incompatibility and undergo meiotic recombination as teleomorphs. Although evidence of recombination in the AF gene cluster has been reported, the impacts of recombination on genotype and metabolomic phenotype in a single generation are lacking. In previous studies, we paired an aflatoxigenic MAT1-1 A. flavus strain with a non-aflatoxigenic MAT1-2 A. flavus strain that had been tagged with green fluorescent protein and then 10 F1 progenies (a mix of fluorescent and non-fluorescent) were randomly selected from single-ascospore colonies and broadly examined for evidence of recombination. In this study, we determined four of those 10 F1 progenies were recombinants because they were not vegetatively compatible with either parent or their siblings, and they exhibited other distinctive traits that could only result from meiotic recombination. The other six progenies examined shared genomic identity with the non-aflatoxigenic, fluorescent, and MAT1-2 parent, but were metabolically distinct. This study highlights phenotypic and genomic changes that may occur in a single generation from the outcrossing of sexually compatible strains of A. flavus.
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Affiliation(s)
- Geromy G Moore
- Southern Regional Research Center, USDA-ARS, New Orleans, Louisiana, USA
| | - Brian M Mack
- Southern Regional Research Center, USDA-ARS, New Orleans, Louisiana, USA
| | - Karen L Wendt
- Department of Chemistry and Biochemistry, Natural Products Discovery Group, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Lina Castano-Duque
- Southern Regional Research Center, USDA-ARS, New Orleans, Louisiana, USA
| | - Victoria M Anderson
- Department of Chemistry and Biochemistry, Natural Products Discovery Group, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Robert H Cichewicz
- Department of Chemistry and Biochemistry, Natural Products Discovery Group, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
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2
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Shehata MG, Alsulami T, El-Aziz NMA, Abd-Rabou HS, El Sohaimy SA, Darwish AMG, Hoppe K, Ali HS, Badr AN. Biopreservative and Anti-Mycotoxigenic Potentials of Lactobacillus paracasei MG847589 and Its Bacteriocin in Soft White Cheese. Toxins (Basel) 2024; 16:93. [PMID: 38393172 PMCID: PMC10891891 DOI: 10.3390/toxins16020093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 10/21/2023] [Accepted: 10/24/2023] [Indexed: 02/25/2024] Open
Abstract
Probiotics and their bacteriocins have increasingly attracted interest for their use as safe food preservatives. This study aimed to produce soft white cheese fortified with Lacticaseibacillus MG847589 (Lb. paracasei MG847589) and/or its bacteriocin; cheese with Lacticaseibacillus (CP), cheese with bacteriocin (CB), and cheese with both Lacticaseibacillus and bacteriocin (CPB) were compared to control cheese (CS) to evaluate their biopreservative and anti-mycotoxigenic potentials for prolonged shelf life and safe food applications. The effects of these fortifications on physiochemical, microbial, texture, microstructure, and sensory properties were studied. Fortification with Lacticaseibacillus (CP) increased acidity (0.61%) and microbial counts, which may make the microstructure porous, while CPB showed intact microstructure. The CPB showed the highest hardness value (3988.03 g), while the lowest was observed with CB (2525.73 g). Consequently, the sensory assessment reflected the panelists' preference for CPB, which gained higher scores than the control (CS). Fortification with Lb. paracasei MG847589 and bacteriocin (CPB) showed inhibition effects against S. aureus from 6.52 log10 CFU/g at time zero to 2.10 log10 CFU/g at the end of storage, A. parasiticus (from 5.06 to 3.03 log10 CFU/g), and P. chrysogenum counts (from 5.11 to 2.86 log10 CFU/g). Additionally, CPB showed an anti-mycotoxigenic effect against aflatoxins AFB1 and AFM1, causing them to be decreased (69.63 ± 0.44% and 71.38 ± 0.75%, respectively). These potentials can extend shelf life and pave the way for more suggested food applications of safe food production by fortification with both Lb. paracasei MG847589 and its bacteriocin as biopreservatives and anti-mycotoxigenic.
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Affiliation(s)
- Mohamed G. Shehata
- Department of Food Technology, Arid Lands Cultivation Research Institute, City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab 21934, Egypt; (M.G.S.); (N.M.A.E.-A.); (S.A.E.S.)
- Food Research Section, R&D Division, Abu Dhabi Agriculture and Food Safety Authority (ADAFSA), Abu Dhabi 20602, United Arab Emirates
| | - Tawfiq Alsulami
- Food Science & Nutrition Department, College of Food and Agricultural Sciences, King Saud University, Riyadh 11451, Saudi Arabia;
| | - Nourhan M. Abd El-Aziz
- Department of Food Technology, Arid Lands Cultivation Research Institute, City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab 21934, Egypt; (M.G.S.); (N.M.A.E.-A.); (S.A.E.S.)
| | - Hagar S. Abd-Rabou
- Department of Food Technology, Arid Lands Cultivation Research Institute, City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab 21934, Egypt; (M.G.S.); (N.M.A.E.-A.); (S.A.E.S.)
| | - Sobhy A. El Sohaimy
- Department of Food Technology, Arid Lands Cultivation Research Institute, City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab 21934, Egypt; (M.G.S.); (N.M.A.E.-A.); (S.A.E.S.)
- Department of Technology and Organization of Public Catering, Institute of Sport, Tourism, and Service, South Ural State University, 454080 Chelyabinsk, Russia
| | - Amira M. G. Darwish
- Department of Food Technology, Arid Lands Cultivation Research Institute, City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab 21934, Egypt; (M.G.S.); (N.M.A.E.-A.); (S.A.E.S.)
| | - Karolina Hoppe
- Chemistry Department, Poznan University of Life Science, ul. Wojska Polskiego 75, 60-625 Poznan, Poland;
| | - Hatem S. Ali
- Food Technology Department, National Research Centre, Cairo 12622, Egypt;
| | - Ahmed Noah Badr
- Food Toxicology and Contaminants Department, National Research Centre, Cairo 12622, Egypt
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Oduro-Mensah D, Lowor ST, Bukari Y, Donkor JK, Minnah B, Nuhu AH, Dontoh D, Amadu AA, Ocloo A. Cocoa-associated filamentous fungi for the biocontrol of aflatoxigenic Aspergillus flavus. J Basic Microbiol 2023; 63:1279-1292. [PMID: 37485741 DOI: 10.1002/jobm.202300163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/30/2023] [Accepted: 07/01/2023] [Indexed: 07/25/2023]
Abstract
Aflatoxin and other mycotoxin contamination are major threats to global food security and present an urgent need to secure the global food crop against spoilage by mycotoxigenic fungi. Cocoa material is noted for naturally low aflatoxin contamination. This study was designed to assess the potential for harnessing cocoa-associated filamentous fungi for the biocontrol of aflatoxigenic Aspergillus flavus. The candidate fungi were isolated from fermented cocoa beans collected from four cocoa-growing areas in Ghana. Molecular characterization included Internal Transcribed Spacer (ITS)-sequencing for identification and polymer chain reaction (PCR) to determine mating type. Effects of the candidate isolates on growth and aflatoxin-production by an aflatoxigenic A. flavus isolate (BANGA1) were assessed. Aflatoxin production was monitored by UV fluorescence and quantified by enzyme-linked immunosorbent assay (ELISA). Thirty-six filamentous fungi were cultured and identified as Aspergillus, Cladosporium, Lichtheimia, or Trichoderma spp. isolates. The isolates generally interacted negatively with BANGA1 growth and aflatoxin production. The Aspergillus niger and Aspergillus aculeatus biocontrol candidates showed the strongest colony antagonism (54%-94%) and reduction in aflatoxin production (12%-50%) on agar. In broth, the A. niger isolates reduced aflatoxin production by up to 97%. Metabolites from the A. niger isolates showed the strongest inhibition of growth by BANGA1 and inhibited aflatoxin production. Four of the candidate isolates belonged to the MAT1-1 mating type and 12 identified as MAT1-2. This may be indicative of the potential for genetic recombination events between fungi in the field, a finding which is particularly relevant to the risk posed by A. flavus biocontrol measures that rely on atoxigenic A. flavus strains.
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Affiliation(s)
- Daniel Oduro-Mensah
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
- African Centre of Excellence for Mycotoxin and Food Safety, Federal University of Technology, Minna, Niger State, Nigeria
| | - Sammy T Lowor
- Physiology/Biochemistry Division, Cocoa Research Institute of Ghana, New Tafo-Akim, Ghana
| | - Yahaya Bukari
- Plant Pathology Division, Cocoa Research Institute of Ghana, New Tafo-Akim, Ghana
| | - Jacob Kwaku Donkor
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Bismark Minnah
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Abdul Hamid Nuhu
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
- Mycotoxins and Histamines Laboratory, Ghana Standards Authority, Accra, Ghana
| | - Derry Dontoh
- Mycotoxins and Histamines Laboratory, Ghana Standards Authority, Accra, Ghana
| | - Ayesha Algade Amadu
- Council for Scientific and Industrial Research-Water Research Institute, Ghana
- Environmental Biology and Health Division, Nanjing University of Science and Technology, Nanjing, Jiangsu Province, China
| | - Augustine Ocloo
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
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Kumar P, Gupta A, Mahato DK, Pandhi S, Pandey AK, Kargwal R, Mishra S, Suhag R, Sharma N, Saurabh V, Paul V, Kumar M, Selvakumar R, Gamlath S, Kamle M, Enshasy HAE, Mokhtar JA, Harakeh S. Aflatoxins in Cereals and Cereal-Based Products: Occurrence, Toxicity, Impact on Human Health, and Their Detoxification and Management Strategies. Toxins (Basel) 2022; 14:toxins14100687. [PMID: 36287956 PMCID: PMC9609140 DOI: 10.3390/toxins14100687] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/27/2022] [Accepted: 09/28/2022] [Indexed: 11/08/2022] Open
Abstract
Cereals and cereal-based products are primary sources of nutrition across the world. However, contamination of these foods with aflatoxins (AFs), secondary metabolites produced by several fungal species, has raised serious concerns. AF generation in innate substrates is influenced by several parameters, including the substrate type, fungus species, moisture content, minerals, humidity, temperature, and physical injury to the kernels. Consumption of AF-contaminated cereals and cereal-based products can lead to both acute and chronic health issues related to physical and mental maturity, reproduction, and the nervous system. Therefore, the precise detection methods, detoxification, and management strategies of AFs in cereal and cereal-based products are crucial for food safety as well as consumer health. Hence, this review provides a brief overview of the occurrence, chemical characteristics, biosynthetic processes, health hazards, and detection techniques of AFs, along with a focus on detoxification and management strategies that could be implemented for food safety and security.
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Affiliation(s)
- Pradeep Kumar
- Department of Botany, University of Lucknow, Lucknow 226007, India
- Applied Microbiology Laboratory, Department of Forestry, North Eastern Regional Institute of Science and Technology, Nirjuli 791109, India
- Correspondence: (P.K.); (D.K.M.)
| | - Akansha Gupta
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
- CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Dipendra Kumar Mahato
- CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
- Correspondence: (P.K.); (D.K.M.)
| | - Shikha Pandhi
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Arun Kumar Pandey
- MMICT&BM(HM), Maharishi Markandeshwar (Deemed to be University), Mullana, Ambala 133207, India
| | - Raveena Kargwal
- Department of Processing and Food Engineering, College of Agricultural Engineering and Technology, Chaudhary Charan Singh Haryana Agricultural University, Hisar 125004, India
| | - Sadhna Mishra
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
- Faculty of Agricultural Sciences, GLA University, Mathura 281406, India
| | - Rajat Suhag
- Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 5, 39100 Bolzano, Italy
| | - Nitya Sharma
- Food and Bioprocess Engineering Laboratory, Centre for Rural Development and Technology, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Vivek Saurabh
- Division of Food Science and Postharvest Technology, ICAR—Indian Agricultural Research Institute, New Delhi 110012, India
| | - Veena Paul
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Manoj Kumar
- Chemical and Biochemical Processing Division, ICAR—Central Institute for Research on Cotton Technology, Mumbai 400019, India
| | - Raman Selvakumar
- Centre for Protected Cultivation Technology, ICAR-Indian Agricultural Research Institute, Pusa Campus, New Delhi 110012, India
| | - Shirani Gamlath
- CASS Food Research Centre, School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Madhu Kamle
- Applied Microbiology Laboratory, Department of Forestry, North Eastern Regional Institute of Science and Technology, Nirjuli 791109, India
| | - Hesham Ali El Enshasy
- Institute of Bioproduct Development, Universiti Teknologi Malaysia (UTM), Skudai 81310, Malaysia
- City of Scientific Research and Technology Applications, New Burg Al Arab, Alexandria 21934, Egypt
| | - Jawahir A. Mokhtar
- Department of Medical Microbiology and Parasitology, Faculty of Medicine, King Abdulaziz University Hospital, Jeddah 21589, Saudi Arabia
- Vaccines and Immunotherapy Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Steve Harakeh
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Yousef Abdul Latif Jameel Scientific Chair of Prophetic Medicine Application, Faculty of Medicine (FM), King Abdulaziz University, Jeddah 21589, Saudi Arabia
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5
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Schamann A, Schmidt-Heydt M, Geisen R. Analysis of the competitiveness between a non-aflatoxigenic and an aflatoxigenic Aspergillus flavus strain on maize kernels by droplet digital PCR. Mycotoxin Res 2021; 38:27-36. [PMID: 34913138 PMCID: PMC8816369 DOI: 10.1007/s12550-021-00447-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 11/12/2021] [Accepted: 12/01/2021] [Indexed: 11/26/2022]
Abstract
Non-aflatoxigenic Aspergillus flavus strains are used as a biocontrol system on maize fields to decrease the aflatoxin biosynthesis of aflatoxigenic A. flavus strains. A. flavus strain AF36 was the first commercially available biocontrol strain and is authorized for use on maize fields by the US Environmental Protection Agency, e.g., in Texas and Arizona. A droplet digital PCR (ddPCR) assay was developed to analyze the mechanisms of competition and interaction of aflatoxigenic and non-aflatoxigenic A. flavus strains. This assay enables the parallel identification and quantification of the biocontrol strain A. flavus AF36 and the aflatoxigenic A. flavus strain MRI19. To test the assay, spores of both strains were mixed in varying ratios and were incubated on maize-based agar or maize kernels for up to 20 days. Genomic equivalent ratios (genome copy numbers) of both strains were determined by ddPCR at certain times after incubation and were compared to the spore ratios used for inoculation. The aflatoxin biosynthesis was also measured. In general, A. flavus MRI19 had higher competitiveness in the tested habitats compared to the non-aflatoxigenic strain, as indicated by higher final genomic equivalent ratios of this strain compared to the spore ratios used for inoculation. Nevertheless, A. flavus AF36 effectively controlled aflatoxin biosynthesis of A. flavus MRI19, as a clear aflatoxin inhibition was already seen by the inoculation of 10% spores of the biocontrol strain mixed with 90% spores of the aflatoxigenic strain compared to samples inoculated with only spores of the aflatoxigenic A. flavus MRI19.
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Affiliation(s)
- Alexandra Schamann
- Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut (MRI) - Federal Research Institute of Nutrition and Food, Karlsruhe, Germany
| | - Markus Schmidt-Heydt
- Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut (MRI) - Federal Research Institute of Nutrition and Food, Karlsruhe, Germany.
| | - Rolf Geisen
- Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut (MRI) - Federal Research Institute of Nutrition and Food, Karlsruhe, Germany
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Ching'anda C, Atehnkeng J, Bandyopadhyay R, Callicott KA, Orbach MJ, Mehl HL, Cotty PJ. Temperature Influences on Interactions Among Aflatoxigenic Species of Aspergillus Section Flavi During Maize Colonization. FRONTIERS IN FUNGAL BIOLOGY 2021; 2:720276. [PMID: 37744097 PMCID: PMC10512225 DOI: 10.3389/ffunb.2021.720276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 07/26/2021] [Indexed: 09/26/2023]
Abstract
Fungal species within Aspergillus section Flavi contaminate food and feed with aflatoxins. These toxic fungal metabolites compromise human and animal health and disrupt trade. Genotypically and phenotypically diverse species co-infect crops, but temporal and spatial variation in frequencies of different lineages suggests that environmental factors such as temperature may influence structure of aflatoxin-producing fungal communities. Furthermore, though most species within Aspergillus section Flavi produce sclerotia, divergent sclerotial morphologies (small or S-type sclerotia vs. large or L-type sclerotia) and differences in types and quantities of aflatoxins produced suggest lineages are adapted to different life strategies. Temperature is a key parameter influencing pre- and post-harvest aflatoxin contamination of crops. We tested the hypothesis that species of aflatoxin-producing fungi that differ in sclerotial morphology will vary in competitive ability and that outcomes of competition and aflatoxin production will be modulated by temperature. Paired competition experiments between highly aflatoxigenic S-type species (A. aflatoxiformans and Lethal Aflatoxicosis Fungus) and L-type species (A. flavus L morphotype and A. parasiticus) were conducted on maize kernels at 25 and 30°C. Proportions of each isolate growing within and sporulating on kernels were measured using quantitative pyrosequencing. At 30°C, S-type fungi were more effective at host colonization compared to L-type isolates. Total aflatoxins and the proportion of B vs. G aflatoxins were greater at 30°C compared to 25°C. Sporulation by L-type isolates was reduced during competition with S-type fungi at 30°C, while relative quantities of conidia produced by S-type species either increased or did not change during competition. Results indicate that both species interactions and temperature can shape population structure of Aspergillus section Flavi, with warmer temperatures favoring growth and dispersal of highly toxigenic species with S-type sclerotia.
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Affiliation(s)
- Connel Ching'anda
- School of Plant Sciences, University of Arizona, Tucson, AZ, United States
| | - Joseph Atehnkeng
- International Institute of Tropical Agriculture (IITA), Lilongwe, Malawi
| | | | - Kenneth A. Callicott
- United States Department of Agriculture - Agriculture Research Service, Tucson, AZ, United States
| | - Marc J. Orbach
- School of Plant Sciences, University of Arizona, Tucson, AZ, United States
| | - Hillary L. Mehl
- United States Department of Agriculture - Agriculture Research Service, Tucson, AZ, United States
| | - Peter J. Cotty
- School of Plant Sciences, University of Arizona, Tucson, AZ, United States
- United States Department of Agriculture - Agriculture Research Service, Tucson, AZ, United States
- College of Food Science and Engineering, Ocean University of China, Qingdao, China
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Peles F, Sipos P, Kovács S, Győri Z, Pócsi I, Pusztahelyi T. Biological Control and Mitigation of Aflatoxin Contamination in Commodities. Toxins (Basel) 2021; 13:toxins13020104. [PMID: 33535580 PMCID: PMC7912779 DOI: 10.3390/toxins13020104] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/23/2021] [Accepted: 01/29/2021] [Indexed: 11/16/2022] Open
Abstract
Aflatoxins (AFs) are toxic secondary metabolites produced mostly by Aspergillus species. AF contamination entering the feed and food chain has been a crucial long-term issue for veterinarians, medicals, agroindustry experts, and researchers working in this field. Although different (physical, chemical, and biological) technologies have been developed, tested, and employed to mitigate the detrimental effects of mycotoxins, including AFs, universal methods are still not available to reduce AF levels in feed and food in the last decades. Possible biological control by bacteria, yeasts, and fungi, their excretes, the role of the ruminal degradation, pre-harvest biocontrol by competitive exclusion or biofungicides, and post-harvest technologies and practices based on biological agents currently used to alleviate the toxic effects of AFs are collected in this review. Pre-harvest biocontrol technologies can give us the greatest opportunity to reduce AF production on the spot. Together with post-harvest applications of bacteria or fungal cultures, these technologies can help us strictly reduce AF contamination without synthetic chemicals.
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Affiliation(s)
- Ferenc Peles
- Institute of Food Science, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Böszörményi str. 138, H-4032 Debrecen, Hungary;
| | - Péter Sipos
- Institute of Nutrition, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Böszörményi str. 138, H-4032 Debrecen, Hungary; (P.S.); (Z.G.)
| | - Szilvia Kovács
- Central Laboratory of Agricultural and Food Products, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Böszörményi str. 138, H-4032 Debrecen, Hungary;
| | - Zoltán Győri
- Institute of Nutrition, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Böszörményi str. 138, H-4032 Debrecen, Hungary; (P.S.); (Z.G.)
| | - István Pócsi
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Egyetem Square 1, H-4032 Debrecen, Hungary;
| | - Tünde Pusztahelyi
- Central Laboratory of Agricultural and Food Products, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Böszörményi str. 138, H-4032 Debrecen, Hungary;
- Correspondence: ; Tel.: +36-20-210-9491
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Dövényi-Nagy T, Rácz C, Molnár K, Bakó K, Szláma Z, Jóźwiak Á, Farkas Z, Pócsi I, Dobos AC. Pre-Harvest Modelling and Mitigation of Aflatoxins in Maize in a Changing Climatic Environment-A Review. Toxins (Basel) 2020; 12:E768. [PMID: 33291729 PMCID: PMC7761929 DOI: 10.3390/toxins12120768] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 11/25/2020] [Accepted: 12/02/2020] [Indexed: 01/13/2023] Open
Abstract
Aflatoxins (AFs) are harmful secondary metabolites produced by various moulds, among which Aspergillus flavus is the major AF-producer fungus. These mycotoxins have carcinogenic or acute toxigenic effects on both humans and food producing animals and, therefore, the health risks and also the potential economic damages mounted by them have led to legal restrictions, and several countries have set maximum allowable limits for AF contaminations in food and feed. While colonization of food and feed and AF production by A. flavus are highly supported by the climatic conditions in tropical and subtropical geographic regions, countries in the temperate climate zones are also increasingly exposed to AF-derived health risks due to climate change. In the present study, we have reviewed the available mathematical models as risk assessment tools to predict the possibility of A. flavus infection and levels of AF contaminations in maize in a changing climatic environment. After highlighting the benefits and possible future improvements of these models, we summarize the current agricultural practices used to prevent or, at least, mitigate the deleterious consequences of AF contaminations.
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Affiliation(s)
- Tamás Dövényi-Nagy
- Agrometeorological and Agroecological Monitoring Centre, AKIT-DTTI, University of Debrecen, H4032 Debrecen, Hungary; (C.R.); (K.M.); (K.B.); (Z.S.); (A.C.D.)
| | - Csaba Rácz
- Agrometeorological and Agroecological Monitoring Centre, AKIT-DTTI, University of Debrecen, H4032 Debrecen, Hungary; (C.R.); (K.M.); (K.B.); (Z.S.); (A.C.D.)
| | - Krisztina Molnár
- Agrometeorological and Agroecological Monitoring Centre, AKIT-DTTI, University of Debrecen, H4032 Debrecen, Hungary; (C.R.); (K.M.); (K.B.); (Z.S.); (A.C.D.)
| | - Károly Bakó
- Agrometeorological and Agroecological Monitoring Centre, AKIT-DTTI, University of Debrecen, H4032 Debrecen, Hungary; (C.R.); (K.M.); (K.B.); (Z.S.); (A.C.D.)
| | - Zsombor Szláma
- Agrometeorological and Agroecological Monitoring Centre, AKIT-DTTI, University of Debrecen, H4032 Debrecen, Hungary; (C.R.); (K.M.); (K.B.); (Z.S.); (A.C.D.)
| | - Ákos Jóźwiak
- Digital Food Institute, University of Veterinary Medicine Budapest, H1078 Budapest, Hungary; (Á.J.); (Z.F.)
| | - Zsuzsa Farkas
- Digital Food Institute, University of Veterinary Medicine Budapest, H1078 Budapest, Hungary; (Á.J.); (Z.F.)
| | - István Pócsi
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, H4032 Debrecen, Hungary;
| | - Attila Csaba Dobos
- Agrometeorological and Agroecological Monitoring Centre, AKIT-DTTI, University of Debrecen, H4032 Debrecen, Hungary; (C.R.); (K.M.); (K.B.); (Z.S.); (A.C.D.)
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Mitema A, Feto NA, Rafudeen MS. Development and validation of TOF/Q-TOF MS/MS, HPLC method and in vitro bio-strategy for aflatoxin mitigation. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2020; 37:2149-2164. [PMID: 33151829 DOI: 10.1080/19440049.2020.1815861] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Some secondary metabolites produced by fungi are carcinogenic, hepatotoxic, and/or cause birth defects in humans and animals. We developed and optimised bio-analytical tools for detection of metabolites, aflatoxins and evaluated the effectiveness of the methods in co-infected maize tissues. Isolate KSM012 (atoxigenic) demonstrated no peaks and no blue fluorescence on HPLC and TLC plates respectively confirming non-toxicity. AFB1 and AFB2 were produced by Isolate KSM015 in addition to AFG1 and AFG2, which is an indication of possible SBG morphotype. The limits of quantification and detection ranged from 0.02 to 35.81 µg/mL and 0.01-6.8 µg/mL, respectively. The best mass spectrum with lowest noise was obtained at 100% ACN and sterile water spiked with 0.1% formic acid at a flow rate of 0.3 mL/min. The positive ion mode with electrospray ionisation application exhibited better fragmentation for mycotoxins. In total 17 metabolites were detected by targeted and formula mass. KDVI maize line exhibited high fungal colonisation in comparison to GAF4 at equal co-infection ratio 50:50. AFB1 and AFG2 were remarkably higher in GAF4 in comparison to sensitive KDV1 (p ˂ 0.05). The detection limits, linearity and sensitivity showed the method developed was suitable for the determination of mycotoxin in comparisons to the guidelines of European Commission 657/EC 2002.
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Affiliation(s)
- Alfred Mitema
- OMICS Research Group, Department of Biotechnology, Vaal University of Technology , Vanderbijlpark, South Africa.,Plant Stress Laboratory, Department of Molecular and Cell Biology, University of Cape Town , Cape Town, South Africa.,School of Biological Sciences, University of Nairobi , Nairobi, Kenya
| | - Naser Aliye Feto
- OMICS Research Group, Department of Biotechnology, Vaal University of Technology , Vanderbijlpark, South Africa
| | - Mohamed Suhail Rafudeen
- Plant Stress Laboratory, Department of Molecular and Cell Biology, University of Cape Town , Cape Town, South Africa
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10
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Ren X, Zhang Q, Zhang W, Mao J, Li P. Control of Aflatoxigenic Molds by Antagonistic Microorganisms: Inhibitory Behaviors, Bioactive Compounds, Related Mechanisms, and Influencing Factors. Toxins (Basel) 2020; 12:E24. [PMID: 31906282 PMCID: PMC7020460 DOI: 10.3390/toxins12010024] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/29/2019] [Accepted: 12/11/2019] [Indexed: 12/21/2022] Open
Abstract
Aflatoxin contamination has been causing great concern worldwide due to the major economic impact on crop production and their toxicological effects to human and animals. Contamination can occur in the field, during transportation, and also in storage. Post-harvest contamination usually derives from the pre-harvest infection of aflatoxigenic molds, especially aflatoxin-producing Aspergilli such as Aspergillusflavus and A. parasiticus. Many strategies preventing aflatoxigenic molds from entering food and feed chains have been reported, among which biological control is becoming one of the most praised strategies. The objective of this article is to review the biocontrol strategy for inhibiting the growth of and aflatoxin production by aflatoxigenic fungi. This review focuses on comparing inhibitory behaviors of different antagonistic microorganisms including various bacteria, fungi and yeasts. We also reviewed the bioactive compounds produced by microorganisms and the mechanisms leading to inhibition. The key factors influencing antifungal activities of antagonists are also discussed in this review.
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Affiliation(s)
- Xianfeng Ren
- Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan 430062, China; (X.R.); (W.Z.); (J.M.)
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Qi Zhang
- Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan 430062, China; (X.R.); (W.Z.); (J.M.)
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
- Key Laboratory of Detection for Mycotoxins, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Wen Zhang
- Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan 430062, China; (X.R.); (W.Z.); (J.M.)
- Key Laboratory of Detection for Mycotoxins, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Jin Mao
- Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan 430062, China; (X.R.); (W.Z.); (J.M.)
- Laboratory of Risk Assessment for Oilseeds Products, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
| | - Peiwu Li
- Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan 430062, China; (X.R.); (W.Z.); (J.M.)
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
- Key Laboratory of Detection for Mycotoxins, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
- Laboratory of Risk Assessment for Oilseeds Products, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
- Quality Inspection and Test Center for Oilseeds Products, Ministry of Agriculture and Rural Affairs, Wuhan 430062, China
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11
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Hettiarachchige IK, Ludlow EJ, Ekanayake PN, Brohier ND, Sahab S, Sawbridge TI, Spangenberg GC, Guthridge KM. Generation of Epichloë Strains Expressing Fluorescent Proteins Suitable for Studying Host-Endophyte Interactions and Characterisation of a T-DNA Integration Event. Microorganisms 2019; 8:E54. [PMID: 31892173 PMCID: PMC7023320 DOI: 10.3390/microorganisms8010054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/20/2019] [Accepted: 12/24/2019] [Indexed: 11/17/2022] Open
Abstract
Methods for the identification and localisation of endophytic fungi are required to study the establishment, development, and progression of host-symbiont interactions, as visible reactions or disease symptoms are generally absent from host plants. Fluorescent proteins have proved valuable as reporter gene products, allowing non-invasive detection in living cells. This study reports the introduction of genes for two fluorescent proteins, green fluorescent protein (GFP) and red fluorescent protein, DsRed, into the genomes of two distinct perennial ryegrass (Lolium perenne L.)-associated Epichloë endophyte strains using A. tumefaciens-mediated transformation. Comprehensive characterisation of reporter gene-containing endophyte strains was performed using molecular genetic, phenotypic, and bioinformatic tools. A combination of long read and short read sequencing of a selected transformant identified a single complex T-DNA insert of 35,530 bp containing multiple T-DNAs linked together. This approach allowed for comprehensive characterisation of T-DNA integration to single-base resolution, while revealing the unanticipated nature of T-DNA integration in the transformant analysed. These reporter gene endophyte strains were able to establish and maintain stable symbiotum with the host. In addition, the same endophyte strain labelled with two different fluorescent proteins were able to cohabit the same plant. This knowledge can be used to provide the basis to develop strategies to gain new insights into the host-endophyte interaction through independent and simultaneous monitoring in planta throughout its life cycle in greater detail.
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Affiliation(s)
- Inoka K. Hettiarachchige
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (I.K.H.); (E.J.L.); (P.N.E.); (N.D.B.); (S.S.); (T.I.S.); (G.C.S.)
| | - Emma J. Ludlow
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (I.K.H.); (E.J.L.); (P.N.E.); (N.D.B.); (S.S.); (T.I.S.); (G.C.S.)
| | - Piyumi N. Ekanayake
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (I.K.H.); (E.J.L.); (P.N.E.); (N.D.B.); (S.S.); (T.I.S.); (G.C.S.)
| | - Natasha D. Brohier
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (I.K.H.); (E.J.L.); (P.N.E.); (N.D.B.); (S.S.); (T.I.S.); (G.C.S.)
| | - Sareena Sahab
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (I.K.H.); (E.J.L.); (P.N.E.); (N.D.B.); (S.S.); (T.I.S.); (G.C.S.)
| | - Timothy I. Sawbridge
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (I.K.H.); (E.J.L.); (P.N.E.); (N.D.B.); (S.S.); (T.I.S.); (G.C.S.)
- School of Applied Systems Biology, La Trobe University, Bundoora, VIC 3083, Australia
| | - German C. Spangenberg
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (I.K.H.); (E.J.L.); (P.N.E.); (N.D.B.); (S.S.); (T.I.S.); (G.C.S.)
- School of Applied Systems Biology, La Trobe University, Bundoora, VIC 3083, Australia
| | - Kathryn M. Guthridge
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, VIC 3083, Australia; (I.K.H.); (E.J.L.); (P.N.E.); (N.D.B.); (S.S.); (T.I.S.); (G.C.S.)
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12
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Aspergillus flavus NRRL 35739, a Poor Biocontrol Agent, May Have Increased Relative Expression of Stress Response Genes. J Fungi (Basel) 2019; 5:jof5020053. [PMID: 31226781 PMCID: PMC6616650 DOI: 10.3390/jof5020053] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 06/16/2019] [Accepted: 06/18/2019] [Indexed: 12/21/2022] Open
Abstract
Biocontrol of the mycotoxin aflatoxin utilizes non-aflatoxigenic strains of Aspergillus flavus, which have variable success rates as biocontrol agents. One non-aflatoxigenic strain, NRRL 35739, is a notably poor biocontrol agent. Its growth in artificial cultures and on peanut kernels was found to be slower than that of two aflatoxigenic strains, and NRRL 35739 exhibited less sporulation when grown on peanuts. The non-aflatoxigenic strain did not greatly prevent aflatoxin accumulation. Comparison of the transcriptomes of aflatoxigenic and non-aflatoxigenic A. flavus strains AF36, AF70, NRRL 3357, NRRL 35739, and WRRL 1519 indicated that strain NRRL 35739 had increased relative expression of six heat shock and stress response proteins, with the genes having relative read counts in NRRL 35739 that were 25 to 410 times more than in the other four strains. These preliminary findings tracked with current thought that aflatoxin biocontrol efficacy is related to the ability of a non-aflatoxigenic strain to out-compete aflatoxigenic ones. The slower growth of NRRL 35739 might be due to lower stress tolerance or overexpression of stress response(s). Further study of NRRL 35739 is needed to refine our understanding of the genetic basis of competitiveness among A. flavus strains.
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13
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Hua SST, Parfitt DE, Sarreal SBL, Sidhu G. Dual culture of atoxigenic and toxigenic strains of Aspergillus flavus to gain insight into repression of aflatoxin biosynthesis and fungal interaction. Mycotoxin Res 2019; 35:381-389. [PMID: 31161589 DOI: 10.1007/s12550-019-00364-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 03/27/2019] [Accepted: 05/06/2019] [Indexed: 11/24/2022]
Abstract
Application of atoxigenic strains to compete against toxigenic strains of Aspergillus flavus strains has emerged as one of the practical strategies for reducing aflatoxin contamination in corn, peanut, and tree nuts. The actual mechanism that results in aflatoxin reduction is not fully understood. Real-time RT-PCR and relative quantification of gene expression protocol were applied to elucidate the molecular mechanism. Transcriptional analyses of aflatoxin biosynthetic gene cluster in dual culture of toxigenic and atoxigenic A. flavus strains were carried out. Six targeted genes, aflR, aflJ, omtA, ordA, pksA, and vbs, were downregulated to variable levels depending on paired strains of toxigenic and atoxigenic A. flavus. Consistent with the decreased gene expression levels, the aflatoxin concentrations in dual cultures were reduced significantly in comparison with toxigenic cultures. Fluorescent images showed fungal hyphae in dual culture displayed green fluorescent, and contacts of live hyphae were seen. A coconut agar plate assay was used to show that toxigenic A. flavus colony produced blue fluorescence under long UV exposure, suggesting that aflatoxin is exported outside fungal hyphae. Furthermore, the assay was applied to demonstrate the potential role of thigmo-regulation in fungal interaction.
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Affiliation(s)
- Sui Sheng T Hua
- U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center, 800 Buchanan Street, Albany, CA, 94710, USA.
| | - Dan E Parfitt
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Siov Bouy L Sarreal
- U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center, 800 Buchanan Street, Albany, CA, 94710, USA
| | - Gaganjot Sidhu
- U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center, 800 Buchanan Street, Albany, CA, 94710, USA
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14
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Mitema A, Okoth S, Rafudeen SM. The Development of a qPCR Assay to Measure Aspergillus flavus Biomass in Maize and the Use of a Biocontrol Strategy to Limit Aflatoxin Production. Toxins (Basel) 2019; 11:toxins11030179. [PMID: 30934573 PMCID: PMC6468655 DOI: 10.3390/toxins11030179] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 03/14/2019] [Accepted: 03/18/2019] [Indexed: 01/10/2023] Open
Abstract
Aspergillus flavus colonisation of maize can produce mycotoxins that are detrimental to both human and animal health. Screening of maize lines, resistant to A. flavus infection, together with a biocontrol strategy, could help minimize subsequent aflatoxin contamination. We developed a qPCR assay to measure A. flavus biomass and showed that two African maize lines, GAF4 and KDV1, had different fungal loads for the aflatoxigenic isolate (KSM014), fourteen days after infection. The qPCR assay revealed no significant variation in A. flavus biomass between diseased and non-diseased maize tissues for GAF4, while KDV1 had a significantly higher A. flavus biomass (p < 0.05) in infected shoots and roots compared to the control. The biocontrol strategy using an atoxigenic isolate (KSM012) against the toxigenic isolate (KSM014), showed aflatoxin production inhibition at the co-infection ratio, 50:50 for both maize lines (KDV1 > 99.7% and GAF ≥ 69.4%), as confirmed by bioanalytical techniques. As far as we are aware, this is the first report in Kenya where the biomass of A. flavus from maize tissue was detected and quantified using a qPCR assay. Our results suggest that maize lines, which have adequate resistance to A. flavus, together with the appropriate biocontrol strategy, could limit outbreaks of aflatoxicoses.
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Affiliation(s)
- Alfred Mitema
- Plant Stress Laboratory 204/207, Department of Molecular and Cell Biology, MCB Building, Upper Campus, University of Cape Town, Private bag X3, Rondebosch, Cape Town 7701, South Africa.
- Department of Botany, School of Biological Sciences, University of Nairobi, P.O. Box 30197, Nairobi 00100, Kenya.
| | - Sheila Okoth
- Department of Botany, School of Biological Sciences, University of Nairobi, P.O. Box 30197, Nairobi 00100, Kenya.
| | - Suhail M Rafudeen
- Plant Stress Laboratory 204/207, Department of Molecular and Cell Biology, MCB Building, Upper Campus, University of Cape Town, Private bag X3, Rondebosch, Cape Town 7701, South Africa.
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15
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Gilbert MK, Mack BM, Moore GG, Downey DL, Lebar MD, Joardar V, Losada L, Yu J, Nierman WC, Bhatnagar D. Whole genome comparison of Aspergillus flavus L-morphotype strain NRRL 3357 (type) and S-morphotype strain AF70. PLoS One 2018; 13:e0199169. [PMID: 29966003 PMCID: PMC6028093 DOI: 10.1371/journal.pone.0199169] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 06/01/2018] [Indexed: 01/03/2023] Open
Abstract
Aspergillus flavus is a saprophytic fungus that infects corn, peanuts, tree nuts and other agriculturally important crops. Once the crop is infected the fungus has the potential to secrete one or more mycotoxins, the most carcinogenic of which is aflatoxin. Aflatoxin contaminated crops are deemed unfit for human or animal consumption, which results in both food and economic losses. Within A. flavus, two morphotypes exist: the S strains (small sclerotia) and L strains (large sclerotia). Significant morphological and physiological differences exist between the two morphotypes. For example, the S-morphotypes produces sclerotia that are smaller (< 400 μm), greater in quantity, and contain higher concentrations of aflatoxin than the L-morphotypes (>400 μm). The morphotypes also differ in pigmentation, pH homeostasis in culture and the number of spores produced. Here we report the first full genome sequence of an A. flavus S morphotype, strain AF70. We provide a comprehensive comparison of the A. flavus S-morphotype genome sequence with a previously sequenced genome of an L-morphotype strain (NRRL 3357), including an in-depth analysis of secondary metabolic clusters and the identification SNPs within their aflatoxin gene clusters.
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Affiliation(s)
- Matthew K. Gilbert
- Food and Feed Safety Unit, USDA, New Orleans, Louisiana, United States of America
- * E-mail:
| | - Brian M. Mack
- Food and Feed Safety Unit, USDA, New Orleans, Louisiana, United States of America
| | - Geromy G. Moore
- Food and Feed Safety Unit, USDA, New Orleans, Louisiana, United States of America
| | - Darlene L. Downey
- Food and Feed Safety Unit, USDA, New Orleans, Louisiana, United States of America
| | - Matthew D. Lebar
- Food and Feed Safety Unit, USDA, New Orleans, Louisiana, United States of America
| | - Vinita Joardar
- The J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Liliana Losada
- The J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - JiuJiang Yu
- Food Quality Laboratory, USDA, Beltsville, Maryland, United States of America
| | - William C. Nierman
- The J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Deepak Bhatnagar
- Food and Feed Safety Unit, USDA, New Orleans, Louisiana, United States of America
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16
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Development of a droplet digital PCR assay for population analysis of aflatoxigenic and atoxigenic Aspergillus flavus mixtures in soil. Mycotoxin Res 2018; 34:187-194. [PMID: 29582253 DOI: 10.1007/s12550-018-0313-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 03/08/2018] [Accepted: 03/13/2018] [Indexed: 10/17/2022]
Abstract
Aflatoxin B1 is a potent hepatotoxin and carcinogen that poses a serious safety hazard to both humans and animals. Aspergillus flavus is the most common aflatoxin-producing species on corn, cotton, peanuts, and tree nuts. Application of atoxigenic strains to compete against aflatoxigenic strains of A. flavus has emerged as one of the most practical strategies for ameliorating aflatoxin contamination in food. Genes directly involved in aflatoxin biosynthesis are clustered on an 82-kb region of the genome. Three atoxigenic strains (CA12, M34, and AF123) were each paired with each of four aflatoxigenic strains (CA28, CA42, CA90, and M52), inoculated into soil and incubated at 28 °C for 2 weeks and 1 month. TaqMan probes, omtA-FAM, and norA-HEX were designed for developing a droplet digital PCR (ddPCR) assay to analyze the soil population of mixtures of A. flavus strains. DNA was extracted from each soil sample and used for ddPCR assays. The data indicated that competition between atoxigenic and aflatoxigenic was strain dependent. Variation in competitive ability among different strains of A. flavus influenced the population reduction of the aflatoxigenic strain by the atoxigenic strain. Higher ratios of atoxigenic to aflatoxigenic strains increased soil population of atoxigenic strains. This is the first study to demonstrate the utility of ddPCR to quantify mixtures of both atoxigenic and aflatoxigenic A. flavus strains in soil and allows for rapid and accurate determination of population sizes of atoxigenic and aflatoxigenic strains. This method eliminates the need for isolation and identification of individual fungal isolates from experimental soil samples.
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17
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Šimončicová J, Kaliňáková B, Kryštofová S. Aflatoxins: biosynthesis, prevention and eradication. ACTA CHIMICA SLOVACA 2017. [DOI: 10.1515/acs-2017-0021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Abstract
Filamentous fungi belonging to Aspergilli genera produce many compounds through various biosynthetic pathways. These compounds include a spectrum of products with beneficial medical properties (lovastatin) as well as those that are toxic and/or carcinogenic which are called mycotoxins. Aspergillus flavus, one of the most abundant soil-borne fungi, is a saprobe that is able growing on many organic nutrient sources, such as peanuts, corn and cotton seed. In many countries, food contamination by A. flavus is a huge problem, mainly due to the production of the most toxic and carcinogenic compounds known as aflatoxins. In this paper, we briefly cover current progress in aflatoxin biosynthesis and regulation, pre- and postharvest preventive measures, and decontamination procedures.
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Affiliation(s)
- Juliana Šimončicová
- Institute of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava , Slovakia
| | - Barbora Kaliňáková
- Institute of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava Slovakia
| | - Svetlana Kryštofová
- Institute of Biochemistry and Microbiology, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava Slovakia
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18
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Hruska Z, Yao H, Kincaid R, Brown RL, Bhatnagar D, Cleveland TE. Temporal Effects on Internal Fluorescence Emissions Associated with Aflatoxin Contamination from Corn Kernel Cross-Sections Inoculated with Toxigenic and Atoxigenic Aspergillus flavus. Front Microbiol 2017; 8:1718. [PMID: 28966606 PMCID: PMC5605554 DOI: 10.3389/fmicb.2017.01718] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 08/24/2017] [Indexed: 11/24/2022] Open
Abstract
Non-invasive, easy to use and cost-effective technology offers a valuable alternative for rapid detection of carcinogenic fungal metabolites, namely aflatoxins, in commodities. One relatively recent development in this area is the use of spectral technology. Fluorescence hyperspectral imaging, in particular, offers a potential rapid and non-invasive method for detecting the presence of aflatoxins in maize infected with the toxigenic fungus Aspergillus flavus. Earlier studies have shown that whole maize kernels contaminated with aflatoxins exhibit different spectral signatures from uncontaminated kernels based on the external fluorescence emission of the whole kernels. Here, the effect of time on the internal fluorescence spectral emissions from cross-sections of kernels infected with toxigenic and atoxigenic A. flavus, were examined in order to elucidate the interaction between the fluorescence signals emitted by some aflatoxin contaminated maize kernels and the fungal invasion resulting in the production of aflatoxins. First, the difference in internal fluorescence emissions between cross-sections of kernels incubated in toxigenic and atoxigenic inoculum was assessed. Kernels were inoculated with each strain for 5, 7, and 9 days before cross-sectioning and imaging. There were 270 kernels (540 halves) imaged, including controls. Second, in a different set of kernels (15 kernels/group; 135 total), the germ of each kernel was separated from the endosperm to determine the major areas of aflatoxin accumulation and progression over nine growth days. Kernels were inoculated with toxigenic and atoxigenic fungal strains for 5, 7, and 9 days before the endosperm and germ were separated, followed by fluorescence hyperspectral imaging and chemical aflatoxin determination. A marked difference in fluorescence intensity was shown between the toxigenic and atoxigenic strains on day nine post-inoculation, which may be a useful indicator of the location of aflatoxin contamination. This finding suggests that both, the fluorescence peak shift and intensity as well as timing, may be essential in distinguishing toxigenic and atoxigenic fungi based on spectral features. Results also reveal a possible preferential difference in the internal colonization of maize kernels between the toxigenic and atoxigenic strains of A. flavus suggesting a potential window for differentiating the strains based on fluorescence spectra at specific time points.
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Affiliation(s)
- Zuzana Hruska
- Geosystems Research Institute, Stennis Space Center, Mississippi State University, StarkvilleMS, United States
| | - Haibo Yao
- Geosystems Research Institute, Stennis Space Center, Mississippi State University, StarkvilleMS, United States
| | - Russell Kincaid
- Geosystems Research Institute, Stennis Space Center, Mississippi State University, StarkvilleMS, United States
| | - Robert L. Brown
- Southern Regional Research Center, United States Department of Agriculture-Agricultural Research Service, New OrleansLA, United States
| | - Deepak Bhatnagar
- Southern Regional Research Center, United States Department of Agriculture-Agricultural Research Service, New OrleansLA, United States
| | - Thomas E. Cleveland
- Southern Regional Research Center, United States Department of Agriculture-Agricultural Research Service, New OrleansLA, United States
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19
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Chalivendra SC, DeRobertis C, Chang PK, Damann KE. Cyclopiazonic Acid Is a Pathogenicity Factor for Aspergillus flavus and a Promising Target for Screening Germplasm for Ear Rot Resistance. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:361-373. [PMID: 28447887 DOI: 10.1094/mpmi-02-17-0026-r] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Aspergillus flavus, an opportunistic pathogen, contaminates maize and other key crops with carcinogenic aflatoxins (AFs). Besides AFs, A. flavus makes many more secondary metabolites (SMs) whose toxicity in insects or vertebrates has been studied. However, the role of SMs in the invasion of plant hosts by A. flavus remains to be investigated. Cyclopiazonic acid (CPA), a neurotoxic SM made by A. flavus, is a nanomolar inhibitor of endoplasmic reticulum calcium ATPases (ECAs) and a potent inducer of cell death in plants. We hypothesized that CPA, by virtue of its cytotoxicity, may serve as a key pathogenicity factor that kills plant cells and supports the saprophytic life style of the fungus while compromising the host defense response. This proposal was tested by two complementary approaches. A comparison of CPA levels among A. flavus isolates indicated that CPA may be a determinant of niche adaptation, i.e., isolates that colonize maize make more CPA than those restricted only to the soil. Further, mutants in the CPA biosynthetic pathway are less virulent in causing ear rot than their wild-type parent in field inoculation assays. Additionally, genes encoding ECAs are expressed in developing maize seeds and are induced by A. flavus infection. Building on these results, we developed a seedling assay in which maize roots were exposed to CPA, and cell death was measured as Evans Blue uptake. Among >40 maize inbreds screened for CPA tolerance, inbreds with proven susceptibility to ear rot were also highly CPA sensitive. The publicly available data on resistance to silk colonization or AF contamination for many of the lines was also broadly correlated with their CPA sensitivity. In summary, our studies show that i) CPA serves as a key pathogenicity factor that enables the saprophytic life style of A. flavus and ii) maize inbreds are diverse in their tolerance to CPA. Taking advantage of this natural variation, we are currently pursuing both genome-wide and candidate gene approaches to identify novel components of maize resistance to Aspergillus ear rot.
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Affiliation(s)
| | | | - Perng-Kuang Chang
- 2 USDA-Southern Region Research Center, New Orleans, LA 70124, U.S.A
| | - Kenneth E Damann
- 1 Louisiana State University Ag Center, Baton Rouge, LA 70803, U.S.A.; and
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Hulikunte Mallikarjunaiah N, Jayapala N, Puttaswamy H, Siddapura Ramachandrappa N. Characterization of non-aflatoxigenic strains of Aspergillus flavus as potential biocontrol agent for the management of aflatoxin contamination in groundnut. Microb Pathog 2017; 102:21-28. [DOI: 10.1016/j.micpath.2016.11.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 11/13/2016] [Accepted: 11/14/2016] [Indexed: 11/25/2022]
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21
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Atehnkeng J, Donner M, Ojiambo PS, Ikotun B, Augusto J, Cotty PJ, Bandyopadhyay R. Environmental distribution and genetic diversity of vegetative compatibility groups determine biocontrol strategies to mitigate aflatoxin contamination of maize by Aspergillus flavus. Microb Biotechnol 2016; 9:75-88. [PMID: 26503309 PMCID: PMC4720411 DOI: 10.1111/1751-7915.12324] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 08/28/2015] [Accepted: 08/30/2015] [Indexed: 02/01/2023] Open
Abstract
Maize infected by aflatoxin-producing Aspergillus flavus may become contaminated with aflatoxins, and as a result, threaten human health, food security and farmers' income in developing countries where maize is a staple. Environmental distribution and genetic diversity of A. flavus can influence the effectiveness of atoxigenic isolates in mitigating aflatoxin contamination. However, such information has not been used to facilitate selection and deployment of atoxigenic isolates. A total of 35 isolates of A. flavus isolated from maize samples collected from three agro-ecological zones of Nigeria were used in this study. Ecophysiological characteristics, distribution and genetic diversity of the isolates were determined to identify vegetative compatibility groups (VCGs). The generated data were used to inform selection and deployment of native atoxigenic isolates to mitigate aflatoxin contamination in maize. In co-inoculation with toxigenic isolates, atoxigenic isolates reduced aflatoxin contamination in grain by > 96%. A total of 25 VCGs were inferred from the collected isolates based on complementation tests involving nitrate non-utilizing (nit(-)) mutants. To determine genetic diversity and distribution of VCGs across agro-ecological zones, 832 nit(-) mutants from 52 locations in 11 administrative districts were paired with one self-complementary nitrate auxotroph tester-pair for each VCG. Atoxigenic VCGs accounted for 81.1% of the 153 positive complementations recorded. Genetic diversity of VCGs was highest in the derived savannah agro-ecological zone (H = 2.61) compared with the southern Guinea savannah (H = 1.90) and northern Guinea savannah (H = 0.94) zones. Genetic richness (H = 2.60) and evenness (E5 = 0.96) of VCGs were high across all agro-ecological zones. Ten VCGs (40%) had members restricted to the original location of isolation, whereas 15 VCGs (60%) had members located between the original source of isolation and a distance > 400 km away. The present study identified widely distributed VCGs in Nigeria such as AV0222, AV3279, AV3304 and AV16127, whose atoxigenic members can be deployed for a region-wide biocontrol of toxigenic isolates to reduce aflatoxin contamination in maize.
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Affiliation(s)
- Joseph Atehnkeng
- Plant Pathology Unit, International Institute of Tropical Agriculture, PMB 5320, Ibadan, Nigeria
| | - Matthias Donner
- Institute for Plant Diseases, Phytopathology and Nematology in Soil Ecosystems, University of Bonn, Bonn, Germany
| | - Peter S Ojiambo
- Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina, USA
| | - Babatunde Ikotun
- Department of Crop Protection and Environmental Biology, University of Ibadan, Ibadan, Nigeria
| | - Joao Augusto
- Plant Pathology Unit, International Institute of Tropical Agriculture, PMB 5320, Ibadan, Nigeria
| | - Peter J Cotty
- USDA-ARS, Division of Plant Pathology and Microbiology, Department of Plant Sciences, University of Arizona, Tucson, Arizona, USA
| | - Ranajit Bandyopadhyay
- Plant Pathology Unit, International Institute of Tropical Agriculture, PMB 5320, Ibadan, Nigeria
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22
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Razzaghi-Abyaneh M, Chang PK, Shams-Ghahfarokhi M, Rai M. Global health issues of aflatoxins in food and agriculture: challenges and opportunities. Front Microbiol 2014; 5:420. [PMID: 25161651 PMCID: PMC4129441 DOI: 10.3389/fmicb.2014.00420] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 07/24/2014] [Indexed: 12/12/2022] Open
Affiliation(s)
- Mehdi Razzaghi-Abyaneh
- Research Laboratory of Fungal Metabolites, Department of Mycology, Pasteur Institute of Iran Tehran, Iran
| | - Perng-Kuang Chang
- Food and Feed Research Unit, Southern Regional Research Center New Orleans, LA, USA
| | | | - Mahendra Rai
- Department of Biotechnology, Sant Gadge Baba Amravati University Amravati, India
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